1. Field of the Invention
This invention relates to an axial piston machine with a plurality of reciprocating pistons, each of which is located so that it can move longitudinally in a cylinder bore and is supported on a bearing surface of a drive plate, whereby the drive plate is oriented at an angle with respect to a transverse plane that is a perpendicular to the axis of rotation of the axial piston machine, thereby forming a tilt angle.
2. Background Information
The prior art includes axial piston machines in a variety of configurations. There are essentially two main groups of axial piston machines: wobble plate construction and swash plate construction. In the axial piston machines that utilize the wobble plate construction, the drive plate rotates, while the cylinder bores in which the respective longitudinally movable reciprocating pistons are located and fixed stationary in relation to the housing. In axial piston machines that utilize the swash plate construction, the drive plate does not rotate in the housing of the axial piston machine, while the cylinder bores of the reciprocating pistons are located in a rotating cylinder drum. Both groups of axial piston machines exist both with a variable and with a constant tilt angle of the drive plate. Theoretically, both groups of axial piston machines can be used as a pump or as a motor.
The size of the stroke of the reciprocating pistons is the determining factor for the volume flow of the axial piston machines, and thus for their performance. The stroke is a function of the tilt angle of the drive plate and increases as the tilt angle increases.
The level of the acceptable stresses in t material (surface pressure, piston deflection) represents the limiting factor for the maximum allowable transverse force on the piston. The maximum transverse force on the piston occurs when the force is split on the drive plate between a longitudinal and transverse force on the piston at the acceptable maximum tilt angle of the drive plate at a specific maximum operating pressure of the axial piston machine. The decisive factor is thereby always the reciprocating cylinder that is extended farthest from its cylinder hole and is exposed to the maximum operating pressure. In particular, high stresses can occur on the edges of the cylinder bore and the reciprocating piston.
To increase the delivery of the axial piston machine, the simplest approach would be to increase the tilt angle of the drive plate. Such an increase, however, would have a disproportional effect on the load on the reciprocating piston because, not only is the transverse force on the piston increased as a function of the tilt angle, but also as a result of the fact that the reciprocating piston is extended farther out of the cylinder bore, a correspondingly increased tilting moment is applied to the extended lever arm.
On the axial piston machines of the prior art, the tilt angle is, therefore, not more than 18 degrees to 20 degrees.